GSTM1 and adenoma: In addition, in patients with advanced adenoma, excluding CRC (n = 103), f-Hb concentration was lower in the PPI-users (n = 56) than in the non-PPI users patients (n = 45) (median and interquartile ranges were: 4.2 μg Hb/g feces [0.0–35.2] vs 26.1 μg Hb/g feces [2.1–139.7], P = 0.025).